Conventionally, the golf club head of a golf club has a plurality of grooves, called score lines, in the face surface thereof.
FIG. 6A and FIG. 6B each show a conventional golf club 100.
The conventional golf club 100 has a plurality of score lines 112 in a face surface 111a of a golf club head 111.
The score lines 112 are arranged approximately parallel to a sole portion 111b. Accordingly, when a player holds the conventional golf club 100 in such a manner that the score lines 112 are parallel to the horizontal ground G, the ground G and the axis of a shaft 115 make a predetermined lie angle α (the state shown in FIG. 6A).
However, in the conventional golf club 100, the sole portion 111b becomes approximately parallel to the ground G, leading to an increase in the length of contact between the sole portion 111b and the ground G, which is likely to cause so-called duffing depending on the course conditions.
In order for the sole portion 111b not to become parallel to the ground G, as shown in FIG. 6B, the player should hold the golf club 100 in such a manner that a lie angle β, which is greater than the lie angle α, is formed. As a result, resistance upon the impact of the golf club head 111 against the ground G can be reduced. This allows the player to swing the golf club 100 all the way, whereby duffing can be prevented.
However, when a player holds the golf club 100 to make the lie angle β greater than the original lie angle α as shown in FIG. 6B, the score lines 112 may be inclined with respect to the ground G. The score lines 112 are an important region that directly contacts a ball when hit. When the score lines 112 are inclined, this may greatly change the driving direction, driving distance, and post-landing behavior of the ball, making it difficult to control the ball.
Incidentally, prior arts examples in which score lines are not parallel to a sole portion are Japanese Patent Application Laid-open Publication No. 2002-360750 and Japanese Patent Application Laid-open Publication No. 2007-307095